From the Urban Health Study, Institute for Health Policy Studies (Dr Watters, Ms Estilo, and Ms Lorvick) and the Department of Family and Community Medicine (Dr Watters), School of Medicine, University of California, San Francisco, and the Prevention Point Research Group, San Francisco, Calif (Mr Clark). Presented in part at the 7th International Conference on AIDS, Florence Italy, June 20, 1991.

Objective.—To evaluate an all-volunteer syringe exchange program in San Francisco, Calif.

Data Sources.—Syringe exchange program records and 11 semiannual surveys administered during a 5.5-year period, using standard questionnaires. Interviews (N=5644) were conducted with injection drug users recruited in two 21-day drug detoxification clinics and three street settings.

Main Outcome Measures.—Use of the syringe exchange program and self-reported data regarding sources of syringes, frequency of injection, initiation into drug injection, and frequency of syringe sharing.

Results.—In spring 1992, 45% reported "usually" obtaining injection equipment from the syringe exchange, and 61% reported using the program within the past year. During the period from December 1986 through June 1992, the median reported frequency of injection declined from 1.9 injections per day to 0.7 injection per day, the mean age increased from 36 to 42 years, and the percentage of new initiates into injection drug use decreased from 3% to 1%. In logistic regression analysis (of fall 1991 through spring 1992 interviews; n=752), we found six independent factors associated with syringe sharing. Protective from syringe sharing were use of the syringe exchange program, having received human immunodeficiency virus (HIV) testing and counseling, condom use, older age, and African-American race. Injection of cocaine was a predictor for syringe sharing. The strength of association between use of the syringe exchange program and not sharing syringes was greatest in injection drug users younger than the median age of 40 years.

Conclusions.—The syringe exchange program was rapidly adopted by injection drug users. Health interventions associated with not sharing needles included use of the syringe exchange program and voluntary, confidential HIV testing and counseling. Our data did not support the hypothesis that a syringe exchange program would stimulate increased drug abuse in terms of frequency of injection or recruitment of new and/or younger users.(JAMA. 1994;271:115-120)